Then I'd try other options first:

> search, search, search, and

> pull codes and post them.

Do you get a check engine light?
Is it the same hot or cold? Does the temp gauge go over half way?
Can you tell if the prob is engine or transmission?
Does it do any better if you select the gears manually?

It might not be a bad idea to start a new thread on the "Engines & Exhaust" forum to attract the eyes of the more mechanically inclined members;
state your prob in the thread title, eg - "04 Limited - low power at start".

Perhaps you can show up at a local Mercedes mechanic, and have a bit of a heart to heart. Once you pop the hood and he sees business on familiar turf, he might want to take on the job. In my case, I had to talk to the service manager at the local Chrysler/Merc dealer, get him to admit that the didn't have an SRT6 tech, and agree to use the Merc techs if needed for diagnosis and QC.